Autism and mental retardation are common and enigmatic disturbances of brain function which generally manifest in early childhood and persist throughout life. Systematic study of unselected series of patients identifies a specific cause in approximately 10% of cases of autism and 50% of cases with mental retardation. Recognized causes are heterogeneous, including genetic defects (e.g., chromosome aberrations, single gene mutations, uniparental disomy), environmental insults (e.g., infection, injury, chemical), or some combination of the two influences (multi-factorial causation). The lack of understanding of causation of many other aspects of autism and mental retardation, including identification of the many responsible genes, the pathogenetic mechanisms through which brain development is adversely affected, and the delineation of the clinical (including behavioral) phenotypes of autism and mental retardation syndromes, underscores the need for clinical research on these mental disabilities. The Greenwood Genetic Center operates a small but productive clinical research program related to autism and mental retardation. Strengths of the program include expertise in dysmorphology, clinical genetics, childhood development, pathology, cytogenetics, biochemical genetics, and molecular genetics. Gaps in expertise include neurology and neuropsychology, epidemiology and biostatistics. The overall goal of the proposed infrastructure support project is to enhance the capacity for the Greenwood Genetic Center, in collaboration with the SC Department of Disabilities and Special Needs, and to conduct clinical research on autism and mental retardation. This will be accomplished of a Section of Neurology/Behavioral Science, 2) developing the capacity to acquires and analyze data through establishment of a Section on Epidemiology and Biostatistic, 3) expansion of the range of molecular technologies and trained manpower available for research purposes, and 4) strengthening the administrative structure in support of the research program through development of an Office of Grants/Research Management and a Scientific Advisory Board.